Geographic Range

Mytilus edulis is found in coastal areas of the northern Atlantic Ocean, including North America, Europe, and the northern Palearctic. They are found from the White Sea in Russia to southern France, throughout the British Isles, with large commercial beds in the Wash, Morecambe Bay, Conway Bay and southwest England, north Wales, and west Scotland. In the west Atlantic, M. edulis occupies the southern Canadian Maritime provinces to North Carolina. ("Fisheries Global Information System (FIGIS)", 2006; "Fisheries Global Information System (FIGIS)", 2006)

Habitat

Mytilus edulis is eurythermal and are able to withstand freezing conditions for several months. Blue mussels are well acclimated to a 5 to 20 °C temperature range, with an upper sustained thermal tolerance limit of about 29 °C for adults. Blue mussels do not thrive in salinities of less than 15%, but can withstand wide environmental fluctuations. Their depth ranges from 5 to 10 meters. Usually, M. edulis is found in subtidal and intertidal beds on rocky shores, and remain permanently attached there. The range of Mytilus edulis is limited by the movement of drifting larval and juvenile stages. ("Fisheries Global Information System (FIGIS)", 2006; Tyler-Walters and Seed, 2006)

Physical Description

Mytilus edulis is characterized by a smooth inequilateral shell, usually purple, blue, or dark brown, which features concentric growth lines emanating from the hinge. The interior of the shell is pearl-white. Internally the mantle has a whitish/yellow color, with a posterior adductor scar significantly larger than its anterior adductor scar. Extending from the closed shell are fibrous brown byssal threads for attachment to a surface. (Tyler-Walters and Seed, 2006)

Development

After the egg is fertilized it turns into a ciliated trocophore larva. The trochophore larva then becomes a veliger, which persists 1 to 1.5 months. In this phase, the larva bears ciliated fan-like protrusions and filter feeds before becoming a juvenile and finding a primary settlement location. The primary settlement location is often located in openings in the substrata, or amongst bryozoans or other filamentous structures and often situated away from mature mussels, presumably to decrease competition. After weeks there, the juvenile has doubled in size and detaches to drift again and find a permanent substrate to which to attach. The young adult will attach to the sea floor with a byssus thread or, if such open substrate is not stable, may attach to another mussel, creating a mussel bed. (Nordsieck, 2006; Tyler-Walters and Seed, 2006)

Reproduction

Mytilus edulis spawns from April to September, depending on water temperature, currents, and other environmental factors. In most populations, resting gonads begin to develop from October to November, with gametogenesis occurring throughout winter so that gonads are mature in early spring. A partial spawning in spring is followed by rapid gametogenesis, with gonads maturing by early summer, resulting in a less intensive secondary spawning in late August or September. Larvae spawned in spring can take advantage of phytoplankton blooms. Occurrence of the secondary spawning is opportunistic, depending on favorable environmental conditions and food availability. Gametogenesis, spawning, and reproductive strategies vary with geographic location. An individual female can produce 5 to 8 million eggs, larger individuals may produce as many as 40 million eggs. In optimal conditions, larval development may be complete in less than 20 days but larval growth and metamorphosis between spring and early summer, at 10 °C, usually takes 1 month. Pediveligers can delay metamorphosis for up to 40 days at 10 °C or for up to 6 months in some cases. (Nordsieck, 2006; Tyler-Walters and Seed, 2006)

Reproductive output is influenced by temperature, food availability, and tidal exposure and can therefore vary from year to year and from place to place.

Breeding season

Blue mussels generally breed during the spring to late summer.

Range number of offspring

5000000 to 40000000

Average number of offspring

7000000

Range age at sexual or reproductive maturity (female)

1 to 2 years

Range age at sexual or reproductive maturity (male)

1 to 2 years

There is no parental care after fertilization.

Parental Investment

no parental involvement

pre-fertilization

provisioning

protecting

female

Lifespan/Longevity

The lifespan of Mytilus edulis may vary considerably depending on attachment location. Settline in more exposed coastal areas make individuals significantly more vulnerable to predation, in large part avian. Quality and stability of the substrate also plays a role in the lifespan. Mussels that settle in exposed locations can experience mortality up to 98% per year. Drifting larval and juvenile stages suffer the highest mortality rates. (Nordsieck, 2006; Tyler-Walters and Seed, 2006)

Range lifespanStatus: wild

18 to 24 years

Behavior

Mytilus edulis is a sessile species, permanently settling on substrates as adults. In loose substrates blue mussels settle together in beds, with younger individuals smothering the older individuals on which they settle. (Nordsieck, 2006; Tyler-Walters and Seed, 2006)

Food Habits

The diet of Mytilus edulis consists of phytoplankton, dinoflagellates, small diatoms, zoospores, flagellates, other protozoans, various unicellular algae, and detritus filtered from the surrounding water. Blue mussels are suspension filter feeders and are considered scavengers, collecting anything in the water column that is small enough to ingest. (Conservation Management Institute, 2001; Tyler-Walters and Seed, 2006)

Predation

Blue mussels are most often found in large mussel beds, where they are somewhat protected from predation by virtue of their numbers. The shell of Mytilus edulis acts as a protective layer, though some predator species are able to crush the shell. (Nordsieck, 2006; Tyler-Walters and Seed, 2006)

Some predators of M. edulis wait until the mussel is forced to open its valves to breathe. The predator then pushes the mussel's siphon into the gap, wedging the mussel open so it can be eaten. (Nordsieck, 2006)

Ecosystem Roles

Mytilus edulis has a high tolerance for increased sediment levels and help to remove sediments from the water column. Large blue mussel beds provide habitat and prey for other animals and act as a substrate for algal attachment, increasing local diversity. Blue mussel larvae are an important food source for plantivorous animals as well. ("Fisheries Global Information System (FIGIS)", 2006; Tyler-Walters and Seed, 2006)

Glossary

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

colonial growth

animals that grow in groups of the same species, often refers to animals which are not mobile, such as corals.

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

food

A substance that provides both nutrients and energy to a living thing.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

native range

the area in which the animal is naturally found, the region in which it is endemic.

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sessile

non-motile; permanently attached at the base.

Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.